Not Applicable
Not Applicable
The present invention relates to an apparatus for delivering a viscous liquid material to a surgical site within the body of a human or an animal. More specifically, it relates to an apparatus for controllably delivering bone cement to a site within a bone that has been surgically prepared to receive the cement.
Many procedures in orthopedic surgery require a predetermined quantity of bone cement to be delivered to a site within a bone that has been surgically prepared to receive the cement. For example, surgery to correct certain spinal injuries or deformities requires a hole to be drilled or bored in a vertebra, and then the hole is filled with bone cement. This is accomplished by filling a syringe with bone cement, and then delivering the cement to the site via a cannula attached to the syringe by a length of flexible tubing.
Because the cement is quite thick and viscous, delivering the cement from the syringe requires a great deal of effort applied to the syringe plunger. Thus, both strength and dexterity are required on the part of the surgeon performing the procedure.
It would thus be an improvement over the current state of the art to provide a mechanism that would facilitate the delivery of bone cement and like materials by making it easier to express the material from the syringe.
Broadly, in one aspect, the present invention is an apparatus for delivering a viscous liquid to a surgical site, comprising a syringe having a barrel and a plunger movable axially within the barrel from a withdrawn position to an inserted position, and a syringe actuation device, wherein the syringe actuation device comprises (1) a hollow, internally-threaded sleeve configured to receive the plunger in its withdrawn position, the sleeve having an open proximal end and a distal end opening configured for securing the syringe barrel; and (2) a substantially cylindrical actuation element having (a) an externally-threaded distal portion dimensioned to screw into the proximal end of the sleeve, and (b) a plunger seat, at the distal end of the actuation element, that bears against the plunger and that pushes the plunger axially toward its inserted position in the barrel as the actuation element is threaded into the sleeve.
In another aspect, the invention is a syringe actuation device for receiving and holding a pre-filled conventional syringe having a barrel containing a measure of liquid and a plunger that is axially movable into the barrel for expressing the contents therefrom, the device comprising a sleeve for securing the pre-filled syringe with the plunger in a withdrawn position and an actuation element that screws into the sleeve so as to push the plunger into the barrel to express the liquid from the syringe.
In a specific preferred embodiment, the actuation device comprises an internally-threaded hollow sleeve with an open proximal end, and a substantially cylindrical actuation element with an externally-threaded distal portion that threads into the open proximal end of the sleeve. The actuation element includes a transverse (i.e., perpendicular to the actuation element axis) plunger seat at its distal end. The sleeve has a longitudinal opening parallel to its axis for receiving the extended plunger of a pre-filled syringe, and a distal end wall portion with an opening or slot through which the barrel of the syringe extends. Also, in the specific preferred embodiment, the proximal portion of the actuation element may be configured as an enlarged-diameter gripping element that is configured to facilitate actuation by increasing the mechanical advantage when the actuation element is screwed into the sleeve.
In use, the actuation element is backed out of the sleeve a sufficient distance in the proximal direction to allow a pre-filled syringe to be installed in the sleeve through the longitudinal opening. The barrel of the syringe being pre-filled with a measured volume of liquid, the plunger of the syringe is in its extended or withdrawn position. The outlet tip of the syringe is connected to one end of a fluid conduit, such as a length of flexible tubing, the other end of which may be coupled to an injection needle or a cannula. As the actuation element is threaded into the sleeve, the plunger seat bears against the plunger to push the plunger distally into the barrel until it reaches its fully inserted position, corresponding to the delivery of the measured volume of liquid from the barrel.
As will be appreciated that the threaded coupling between the actuation element and the sleeve allows the actuation element to be turned as a screw within the sleeve and to advance against the plunger with the mechanical advantage provided by a screw mechanism. This screwing action, in turn, allows the user more easily to apply sufficient force to the plunger to express a highly viscous liquid (e.g., bone cement) from the barrel. Furthermore, a greater degree of control can be used in actuating the plunger. For example, stopping the plunger at precise positions within the barrel, so as to express the contents of the barrel in desired increments, is greatly facilitated. These and other advantages of the invention will be more fully understood from the detailed description that follows.